The present invention relates generally to mobile communication networks having a distributed architecture, and more particularly to a PDSN-based system and method of reestablishing a network connection to a mobile station following failure of a RBS.
Most radio access networks (RANs) employed today use a hierarchical network architecture in which each higher level entity supports multiple lower level entities. High rate packet data (HRPD) networks according to the Third Generation Partnership Project 2 (3GPP2) standard exemplify this type of hierarchical network. In HRPD networks, a packet control function performing session control and mobility management functions connects multiple base station controllers (also known as access node controllers) to the core network. Each base station controller, in turn, connects to multiple radio base stations and performs radio resource control functions. The radio base stations communicate over the air interface with the mobile stations. This conventional hierarchical architecture has worked well for voice services and most packet data services.
HRPD networks are now evolving toward a distributed architecture in which the radio base station, base station controller, and packet control function are integrated into a single node referred to herein as an access node (AN). The ANs help reduce the amount of hardware in the network by taking advantage of spare processing capacity in the radio base station. In the new distributed architecture, functions traditionally performed by centralized nodes, such as session management and mobility management, are distributed among a plurality of network nodes. This architecture enhances robustness by eliminating critical central network nodes, the failure of which could cripple entire segments of the network.
In the distributed architecture, critical information such as session management information is duplicated among two or more ANs. If the AN providing a data link to a mobile station fails, another AN maintains the information necessary to reestablish the HRPD communication sessions with the mobile station, and to reroute packet data through the network to reach the mobile station. By encoding the identification of this AN into a session identification tag assigned to the mobile station, when the mobile station requests access to the system, any AN receiving the access request can locate the AN storing the HRPD session information, by inspection of the mobile station's identifier. However, if the AN anchoring the network connection fails and the mobile station is dormant, it may become unreachable from the network perspective, as the core network is unable to page the mobile station to force it to access the network. The core network does not know the identification assigned to the mobile station, or to which time slot the mobile station has been assigned.